A lot of tools promise to give your AI memory. Most keep that memory on their servers. Here's an honest look at how Second Brain, self-hosted, open source, free at personal scale, stacks up against the popular alternatives.
Detailed, fair breakdowns, including where each alternative genuinely wins.
A developer memory API and cloud platform. We compare ownership, pricing, graph memory, and who actually stores your data.
Read comparisonA cloud vault that auto-extracts from your apps. We compare custody, how things get in, open source, and cost.
Read comparisonA capable local-first memory engine for coding agents. We compare reach, devices, tool breadth, and ownership.
Read comparisonThe fundamentals across all four, side by side.
| Second Brain | Mem0 | Unabyss | Agent-Memory | |
|---|---|---|---|---|
| Category | Personal memory you own | Memory API for devs | Cloud vault | Local memory for coding agents |
| Where it runs | Your Cloudflare account | Self-host or cloud | Vendor cloud | One local machine |
| Open source | MIT | Apache 2.0 | No | MIT |
| You own the data | Always | Self-host only | Hosted for you | Local |
| Free at personal scale | Yes | Free tier / paid cloud | $50 credits, then PAYG | Yes |
| MCP-native | + OAuth | Yes | Yes | Yes |
| Multi-device | Yes | Yes | Yes | No |
| Ready-made apps | CLI · Obsidian · browser · iOS | SDKs · browser · CLI | Web app · MCP | CLI · agent skills |
| Best for | Owning one private brain across every tool | Shipping memory inside your product | Hands-off, auto-built cloud service | One dev's coding agents, offline |
Competitor details reflect each product's public site, repo and listings as of mid-2026 and may change, follow the links in each comparison to verify. Any retrieval-accuracy or token-savings benchmarks cited by these tools are vendor-reported, not independently verified here.
Each alternative is good at something, Mem0 at developer flexibility, Unabyss at hands-off cloud convenience, Agent-Memory at pure-local simplicity. But they ask you to make a trade: keep your memory on a vendor's servers, pay a meter as it grows, or scope it to a single machine.
Second Brain's whole premise is that you shouldn't have to choose. Self-hosted, so you own it. Everywhere, so it follows you. Open source, so you can check it. Free at personal scale, so it stays yours.
Lives only in your Cloudflare account, no platform in the middle.
Same brain in Claude, ChatGPT, Cursor, the terminal and your phone.
Dedup, contradiction detection, smart-merge and time-decay built in.
MIT licensed, runs on Cloudflare's free tier at personal scale.
The desktop app sets it up on your own Cloudflare account in two minutes. Free at personal scale. MIT licensed.